Kansas State University (KSU) researchers found no advantage to feeding chlortetracycline for four 5-day periods after mass-medicating stocker calves at receiving with a long-lasting, injectable therapeutic antimicrobial (Tulathromycin).

This was for a 55-day receiving period; high-risk calves received on three consecutive days in May 2008.

In their study, the folks at KSU compared three treatment groups of cattle receiving rations that included:

  • No top-dress pellets (control);
  • Top-dressing with pellets containing 10 mg of chlortetracycline per pound of bodyweight on days 8-12, 14-18, 20-24, and 26-30 post-arrival;
  • Top-dressing with pellets containing 10 mg of chlortetracycline per pound of bodyweight on days 0-4, 6-10, 12-16, 18-22, and 24-28. This was followed by 25 days of administration of 350 mg/head/day of both chlortetracycline and sulfamethazine.
Calves were stepped up using three sequential growing diets ranging from 29% to 36.5% concentrate. All treatments received Bovatec at 250-300 mg/head daily in the complete feed for the first 28 days on study. The control and chlortetracycline-only treatments received Bovatec from day 29 until conclusion of the study.

According to researchers, there were no significant differences among treatments in the percentage of steers treated once, twice, or one or more times for bovine respiratory disease. There were no significant differences in daily gain, daily dry matter intake or feed efficiency among the three treatments.

You can find complete results in the proceedings of the 2010 KSU Cattlemen’s Field Day at www.ksre.ksu.edu/